ABBOTTABAD, Pakistan (AP) - Four helicopters swooped in early Monday and killed Osama bin Laden in a fiery American raid on his fortress-like compound in a Pakistani town that is home to three army regiments. His location raised pointed questions of whether Pakistani authorities knew the whereabouts of the world's most wanted man.

The al-Qaida chief was living in a house in the town of Abbottabad that a U.S. official said was "custom built to hide someone of significance." Abbottabad is around 60 miles from the capital Islamabad, a far cry from the remote mountain caves along the Pakistan-Afghanistan tribal border where most intelligence assessments had put bin Laden in recent years.

Residents said the compound was around one kilometer (half a mile) away from the Kakul Military Academy, an army run institution for top officers and one of several military installations in the bustling, hill-ringed town of around 400,000 people.

An American administration official said the compound was built in 2005 at the end of a narrow dirt road with "extraordinary" security measures. He said it had 12 to 18-feet walls topped with barbed wire with two security gates and no telephone or Internet service connected to it.

A Pakistan intelligence official said the property where bin Laden was staying was 3,000 square feet.

Critics have long accused elements of Pakistan's security establishment of protecting bin Laden, though Islamabad has always denied this. Ties between the United States and Pakistan have hit a low point in recent months over the future of Afghanistan, and any hint of possible Pakistani collusion with bin Laden could hit them hard even amid the jubilation of getting American's No. 1 enemy.

Pakistan's government and army are very sensitive to concerns that they are working under the orders of America and allowing U.S. forces to operate here. Some critics assailed Pakistan for allowing the operation and tried to appeal to nationalist sentiments, while at least one Islamist party was planning a protest against the killing of man idolized by militants inside Pakistan.

Pakistan's former President Pervez Musharraf, who is eyeing a political comeback, said the "killing was the success of all peace loving people of the world." But he also said the Americans should not have been allowed to operate independently in the country.

One Pakistani official said the choppers took off from a Pakistani air base, suggesting some cooperation in the raid. President Barack Obama said Pakistan had provided some information leading to the raid, did not thank the country in his statement on bin Laden's death.

Pakistan's intelligence agency and the CIA have cooperated in joint raids before against al-Qaida suspects in Pakistan on several occasions since the Sept. 11, 2001 attacks. But U.S. and Pakistani officials indicated that this mission was too important to let anyone know more than a few minutes in advance.

Pakistan's foreign office hailed the death as a breakthrough in the international campaign against militancy, and noted al-Qaida "had declared war on Pakistan" and killed thousands of Pakistani civilians and security officers.

It stressed that the operation to kill bin Laden was an American one, and did not mention any concerns that Pakistani officials may have been protecting bin Laden in some way. Domestically, the already weak government may yet face criticism by political opponents and Islamists for allowing U.S. forces to kill bin Laden on its soil, but there were no signs of a major backlash Monday.

Pakistani officials said a son of bin Laden and three other people were killed. Other unidentified males were taken by helicopter away from the scene, while four children and two woman were arrested and left in an ambulance, the official said.

A witness and a Pakistani official said bin Laden's guards opened fire from the roof of the compound in the small northwestern town of Abbottabad, and one of the choppers crashed. However U.S. officials said no Americans were hurt in the operation. The sound of at least two explosions rocked Abbottabad as the fighting raged.

It was not known how long bin Laden had been in Abbottabad, which is less than half a day's drive from the border region with Afghanistan. But Pakistani intelligence agencies are normally very sharp in sniffing out the presence of foreigners, especially in towns with a heavy military presence.

Locals said large Landcruisers and other expensive cars were seen driving into the compound, which is in a regular middle-class neighborhood of dirt covered, litter-strewn roads and small shops. Cabbage and other vegetables are planted in empty plots in the neighborhood.

Salman Riaz, a film actor, said that five months ago he and a crew tried to do some filming next to the house, but were told to stop by two men who came out.